Change search
ReferencesLink to record
Permanent link

Direct link
Enhanced MJO and transition to superrotation in warm climates
Stockholm University, Faculty of Science, Department of Meteorology .
Stockholm University, Faculty of Science, Department of Meteorology .
Number of Authors: 2
2016 (English)In: Journal of Advances in Modeling Earth Systems, ISSN 1942-2466, Vol. 8, no 1, 304-318 p.Article in journal (Refereed) Published
Abstract [en]

Using the NCAR CAM3 model in aquaplanet configuration, we perform a suite of simulations spanning a broad range of warm climates. The simulations show a spontaneous transition to superrotation, i.e., westerly winds at upper levels above the equator. The momentum convergence leading to superrotation is driven by eastward-propagating equatorial waves with structure similar to the modern Madden-Julian Oscillation (MJO), whose amplitude increases strongly with temperature. We analyze the moist static energy (MSE) budget of the model's MJO to identify mechanisms leading to its enhanced amplitude. Two such mechanisms are identified: a rapid increase of mean low-level MSE with rising temperature, as found in previous work, and reduced damping of the MJO by synoptic-scale eddies. Both effects imply a reduced gross moist stability and enhanced MJO amplitude. The reduced eddy damping is caused by the transition to superrotation, which allows a greater penetration of extratropical eddies into the equatorial zone; the dominant effect of this greater penetration is to flatten the meridional gradient zonal-mean MSE, which effectively impedes the generation of anomalous MSE divergence by MJO-modulated eddies. This mechanism implies a positive feedback between superrotation and the MJO which may hasten the transition into a strongly superrotating state.

Place, publisher, year, edition, pages
2016. Vol. 8, no 1, 304-318 p.
Keyword [en]
MJO, superrotation
National Category
Earth and Related Environmental Sciences
Identifiers
URN: urn:nbn:se:su:diva-130981DOI: 10.1002/2015MS000615ISI: 000374770200015OAI: oai:DiVA.org:su-130981DiVA: diva2:936214
Available from: 2016-06-13 Created: 2016-06-09 Last updated: 2016-06-13Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Carlson, HenrikCaballero, Rodrigo
By organisation
Department of Meteorology
In the same journal
Journal of Advances in Modeling Earth Systems
Earth and Related Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 42 hits
ReferencesLink to record
Permanent link

Direct link